1. Field of the Invention
The present invention relates to a damping system able to suppress vibration of any vibrating body including buildings, various machines, or vehicles.
2. Description of the Related Arts
Known in the prior art is a damping system for decreasing the vibration in a vibrating body, and having a damper providing a damping ability based on the viscosity of a fluid such as oil. In this type of damper, an orifice is provided in a piston connected to the vibrating body, and the viscosity of the fluid causes a resistance force to be generated in the piston when the fluid passes through the orifice. This resistance force allows a damping function to be imparted to the vibrating body. Furthermore, for a rotating shaft, a damping system is known where an annular slit is formed between the bearing assembly and support body, which creates an annular film of fluid in the annular slit. When the shaft is vibrated, the film of viscous fluid in the slit is squeezed to obtain a damping effect. (See Japanese Unexamined Patent Publication Nos. 54-96650 and 57-1822).
The damping effect provided by these prior art dampers is based on the viscosity of a fluid in an orifice(s), which determines a damper ratio. In these prior arts, the damper system, however; has only one damping ratio, and this cannot be varied after the damping system is assembled. This means that a desired damping effect can be obtained only when the damper is used for a vibrating system having a designated characteristic. Namely, a desired damping effect can not be obtained when the damper is used for a vibrating system other than that designated. Furthermore, the prior art damping system can not obtain a desired damping effect when used for a vibrating member having vibrating characteristic which is changed in accordance with a lapse of time.